New creature type: Sandbugs
Our new race living in the Glassdunes looks like Sandshrew, with chieftains similar to Sandslash:
The following has been proposed by Jimmy Groove:
These desert creatures, called Sandbugs, have some insectoid characteristics, for example they have a set of powerful digging chitinous forelimbs, then a hybrid mammalian-insect appearance for the rest of they body. This way we can also easily have different casts and it allow us to add things like flying to them as needed.
Thinking about Sandbugs and trying to find a good mechanical identity for them, we decided to go with the following (proposed by Piar):
Whenever this creature becomes blocked, you may return it to its owner's hand.
Not all Sandbugs are meant to have this ability, but it should appear on multiple ones (now supposed to be just a vertical cycle), and the others should interact with it someway.
Having this ability matter in combat makes sense in red and returning creatures to your hand is white, so this fits in the intended flavor of them being red/white creatures living in the Glassdunes (red/white desert). No need to change their original flavor identity or the red/white environment.
A particular kind of Sandbugs, called "Glasskippers", while not particularly gifted for fighting, have the ability to travel through the Glassdunes at great pace. They are taught to put the lives of others before those of theirselves. They patrol vast desert areas around the nests and look for any signs of danger, be them hellions, winged invaders, or anything else.
Creature types
Jimmy Groove proposed the following.
What if we make the role that would normally be filled by "class" in most sets fulfilled by a modifier that represents ecological niche instead, with these based on the way the plane is affecting the growth of the creatures.
No modifier: This is a creature that is very similar to something we might see on Earth (a 3/3 Trampling elephant as just an Elephant)
Elemental: This is a creature that has developed a purely magical ability, but otherwise has a fairly normal form (a 1/1 fireabreathing lizard might be an Elemental Lizard)
Beast: This is a creature that has developed along lines that are at least theoretically possible, but unlikely (a 4/4 frog with reach might be a Beast Frog). Creatures like Baloths with no real-world counterparts might just be Beasts.
Spirit: This is a creature that has died, but still maintains basically the same motivations as in life, but possibly expanded. A wolf that can support any creature by providing a +1/+1 bonus by tapping might be a Spirit Wolf.
Mutant: These are creatures that are are either both magical and hyper-evolved, or totally bizarre, like giant, scrying insects or creatures with abilities that are hard to imagine any real world creature having.
Horror: Creatures emerged from the Sphere. Fusions of multiple creatures might just be Horror without a subtype.
Doing it this way, environments with a lot of elemental magic affecting creatures (like the Crackling Reefs) might have more Elementals and be the environments that might support any theoretical Elemental tribal elements. Environments that are just hyper-versions of normal environments would favor Beasts. Environments where creatures die a great deal might favor Spirits, and environments tied to the Sphere in some way would have Horrors associated with them. And "Beast Tribal" represents creatures that have developed to fit the current ecosystem amazingly well, reinforcing the "wild, but different" nature.
List of creature types
Here is the whole list of existing creature types from the Comprehensive Rules (DTK Edition, the latest available at this time, Rule 205.3m), along with my opinion on whether I can see them living on Extinctia or not. In spoiler because it's very long.
